Apple Lossless Audio Coding
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- FOURCCS: alac
- Company: Apple
- Technical Description: http://craz.net/programs/itunes/alac.html
Lossless audio coding using linear prediction with Golomb-Rice coding of the difference. Similar to FLAC, although the bitstreams are not compatible. Usually stored in an MP4 container, as a private extension since it is not part of the MPEG-4 standard.
Frame Header
| Syntax | Number of bits | Semantics |
|---|---|---|
| channels | 3 | Number of channel -1 (Should be the same than in extradata ???) |
| ??? | 4 | ??? |
| ??? | 12 | ??? |
| hassize | 1 | the output sample number is stored in the header |
| wasted_bytes | 2 | unknow (same as flac ???) |
| isverbatim | 1 | if 1, the data is not compressed |
| if (hassize) { | ||
| outputsamples | 32 | number of samples |
| } |